let r = square(10);
console.log(r);

// 提升(声明前置)
function square(x) {
    return x * x;
};
// 不会被提升
let fun = function () {
    console.log("fun()");
}



function getAge(n) {

    function getA() {
        let a = 1;
        return n;
    }
    return getA;
}

r = getAge(5);
getAge(6);
console.log(r());

function f(a) {
    console.log(a);
}

f(r)